Render issues, says disk is full?

I tried to render a small project in Adobe After Effects, and after about 7 minutes I heard a "baaa" sound(or something close to it) with a notification that the render failed and "disk full" and that the "file may be corrupt." The flash drive I was rendering it to certainly had enough space, and when I tried rendering it again it failed at around the same time, and interestingly what was left of the semi-rendered file was the same size as the previous one. 4,179,644 KB to be exact. Why is this happening? What can I do to fix it? Help would be much appreciated.